Cycle-Based Sleep Coaching

3. The system of claim 2, wherein the server adjusts the recommended time in bed by decreasing the recommended time in bed during an early follicular phase of the menstrual cycle and increasing the recommended time in bed during a late luteal phase of the menstrual cycle.

5. The method of claim 4, wherein identifying the hormonal cycle and the phase includes identifying the hormonal cycle and the phase based on heart rate data.

6. The method of claim 5, wherein identifying the phase within the hormonal cycle includes identifying the phase based on a pattern of change in a heart rate variability for the user over a period of the hormonal cycle.

7. The method of claim 5, wherein identifying the phase within the hormonal cycle includes determining a respiratory rate for the user based on a heart rate variability for the user and identifying the phase based on a pattern of change in the respiratory rate.

8. The method of claim 4, wherein identifying the phase within the hormonal cycle includes training a machine learning model to detect the phase within the hormonal cycle based on one or more of a respiratory rate and a resting heart rate for the user.

9. The method of claim 4, wherein identifying the hormonal cycle and the phase includes identifying the hormonal cycle and the phase based on user input.

10. The method of claim 4, wherein identifying the hormonal cycle and the phase includes identifying the hormonal cycle and the phase based on a skin temperature measured for the user with the wearable physiological monitoring device.

11. The method of claim 4, wherein the current sleep need is based on one or more of a current daily strain, a prior strain, a heart rate variability, a resting heart rate, and a respiratory rate for the user.

12. The method of claim 4, wherein the prior sleep history for the user includes a duration of sleep for a prior sleep event.

13. The method of claim 4, wherein the first recommended time in bed includes a time selected to satisfy the current sleep need based on an historic ratio of time in bed to time asleep for the user.

14. The method of claim 4, wherein the hormonal cycle is a menstrual cycle.

15. The method of claim 14, wherein adjusting the first recommended time in bed includes decreasing the first recommended time in bed during an early follicular phase of the menstrual cycle.

16. The method of claim 14, wherein adjusting the first recommended time in bed includes increasing the first recommended time in bed during a late luteal phase of the menstrual cycle.

17. The method of claim 4, wherein the heart rate data spans at least twenty-eight days for the user.

18. The method of claim 4, wherein the heart rate data is captured substantially continuously by the wearable physiological monitoring device.

19. The method of claim 4, further comprising presenting the second recommended time in bed to the user in a user interface.

20. The method of claim 4, further comprising transmitting the heart rate data to a server for remote processing and transmitting the second recommended time in bed from the server to a local device for viewing by the user.